Fluid pressure compounding system



June 5, 1-945. s. SCHNELL FLUID PRESSURE COMPOUNDING SYSTEMS Filed July 2, 1943 INVEN TOR S.v SCH NE LL ATTORNEY parent from the 1101] cited! June 5, 1945 illl li Electric Corporation, St. Louisa tion of Delaware Application July 2, 194$,Serial No. 493,233

12 Claims.

My invention relates to fiuidpressure systems and more particularly to a system wherein the fluid pressure from the source can be compounded or boosted.

One or the objects of my invention is to produce an improved compounding unit for interpositioning between a source of fluid pressure and a device to be actuated, which unit is so constructed that it will function automatically when the fluid pressure from the source is above a predetermined value.

Another object of my invention is to produce unimproved compounding unit which will not be caused to function prematurely when a sudden high fluid pressure is developed at the source but does not immediately become effective in the device to be actuated. v

Other objects of my invention will become apowing description taken in connection with the accompanying drawing in which Figure 1 is a schematic showing of a fluid pressure system having a compounding device embodying my invention, said compounding de vice being shown an enlarged partial sectional view; and Figure 2 is a sectional view showing valve structure details.

Referring to the figures in detail, the fluid preslllo, a corpora- Positioned within the larger cylinder it is a ducts We, only two of which are shown. The

sure system comprises essentially three units,

namely, a pressure producing unit in the form of a'master cylinder device A, an actuated unit B, and an improved compounding unit C. The master cylinder device comprises a cylinder I having reciprocable therein a piston 2 connected by a a brake pedal 4. The piston is normally biased to its inoperative position by a spring 5 and when it is in this position, it uncovers a porthole Ii to place the cylinder ahead oi! the piston in communication with a reservoir 1. The outlet of the master cylinder device is connected to the compounding unit C by a conduit 8. The actuated unit B is shown as a brake but may be ed by a hollow shell it is closed at the end adjacent port ll by a plug which is provided with a cylindrical extension 2l for telescopic reception in guides 22 on the inner side of plug it. The other or forward end of shell It is provided with a reduced extending portion 28 having slots 23"111 its end and mounted on this portion is a yieldable valve element 23. This valve element has an annular sealing rib 25 for cooperation with the surface 26 at the junction ends of cylinders l3 and Ill.

The inner end of cylinder I3 is provided with an outlet port 2! communicating with a passage 28 in the wall of the casing. A fitting 29 connects passage 28 to conduit H which, as previously mentioned, communicates with the fluid motor 02' thebrake assembly. Passage 28 is provided with a check valve 30 biased to closed position by a spring-3|. The check valve permits fluid to flow from cylinder I3 through-port 2.1 to conduit I l but prevents any return flow of fluid back through port 21. A passage 32 is provide for placing the inner end of shell cation with passage 28 and conduit I I when valve element 24 is seated.

Within shell I8 is a piston 3 der I [is a piston .34, said piston rod 85 integral with piston A retracting spring 36 is interposed between (1 in the casing 3 and within cylin- 1 the closure plug I5 of cylinder I4 and the con- .n'ected pistons 33'and 34 in order to bias them toward their inoperative positions, which positions are determined by the abutting of the coder shell any other device which it is desired to actuate.

assembly! is operated by a fluid mo-' to which conduit I iswnnected in order that cylinder II can receive veloped by the master cylinder devi pressured e 1 s n I8 against closure plug I6. Under these conditions piston 34 abuts the end of extension 23 on shell II. With the pistons and shell I8 in their inoperative positions, a chamber 31 exist between piston 33; and the end plug, 20 or the shell. 33 and 34 have associated there with packing cups 3! and 39, respectively, which are so emaciated with the pistons as to prevent fluid from the pistons Irom'the space pistons.

betweenthe Theplusllclosingtheendotshell llisprovided with a bore 48 having a reduced inner end provided with a port I placing the bore in communlcatlonwith chamber 31 between plug 20 and] n 33. In bore ll is a piston 42 having a, sealmg cup 43 on-the side toward the inlet port I1.

I8 in'communipistons being connect-' the guides of plug ,to the position shown.

"strength to hold it in one of its forward positions.

The valve element 48 cooperates with the inner end of passage 44 in piston 42 to thus normally close this passage. Since spring 49 is substantially stronger than light spring 45 acting on piston 42, the valve element will engage and move piston 42 away from the end of bore 48 when piston 33 is in its retracted position as determined by spring 88.

Referring to the operation of the improved fluid pressure compounding system just described, the parts of the compounding unit will be in the positions shown when the master cylinder device is not being operated. Under these conditions spring 38 will move pistons 33 and 34 so that pisten 34 will engage the end of the shell and move it so plug 28 in the other end thereof will engage [6 of thecasing, Passage 44 will be closed by valve element 48. Valve element 24 carried by the shell will be unseated from surface 26.

If fluid under pressure is developed by the master cylinder device, it will enter port 11 of the compounding unit and act on plug 28 of shell l8, thus forcing this shell to the right against the action of spring 38 and causing valve element 24 at the forward end of the shell to become seated on surface 28. The movement of the shell also carries with it pistons 33 and 34 and there will be no change in their relative positions. Fluid pressure is free to flow past check valve 30 and into fluid motor III of the brakes, which fluid will have the same pressure as that developed by the master cylinder device. The same fluid pressure will also be present in the inner part of shell l8 ahead of piston 38 and act on this piston and piston 34. Since the net effective area of piston 33 is considerably smaller than the area of plug 28 and both areas are acted upon by th same fluid pressure, the shell will be maintained in the forward position in order to hold valve element 24 seated by differential pressure. Thev retracting spring 38 is only strong enough to return the pistons to their inoperative positions and displace piston 42 Th fluid pressure developed by the master cylinder device will also be effective in passage 44 of piston 42 and act on the exposed end of valve element 48. The same fluid pressure will act on piston 42 and such pressure will move piston 42 and the closed-valve element 48 to the right until piston 42 abuts the the brakes than posed to fluid pressure in passage 44. For the purpose of this description, the predetermined value can be assumed as being one hundred pounds per square inch. When valve element 48 becomes unseated, fluid under pressure will enter chamber 31 and increase the pressure therein. This increased pressure will then act on piston 33 and move this piston to the right relatively to shell l8. Since piston 33 is connected to piston 34, the two pistons will be moved in unison and due to the fact that the forward area of piston 33 is larger than the rear area of piston 34, fluid pressure will be developed by piston 33 and forced out of passage 32 and into conduit ll behind check valve 30, This fluid pressure will be greater than that developed by the master cylinder device due to the fact that the area of piston 33 acted upon by the fluid pressure from the master cylinder device is greater than the area of piston 33 minus the area of piston 34. Thus there will be a ratio established between the fluid pressure developed by the master cylinder device and the fluid pressure of the fluid motor, which ratio will be determined by the areas of the various pistons. When pistons 33 and 34 are moved to the right as a result of the opening of valve element 48,-a compounding action will be present which will boost the master cylinder, developed pressure and thus the manual force being applied to the pedal of the master cylinder device will be less to apply tion were present, that is, the compounding unit eliminated.

reduced end of bore 48. Movement of piston 42 to the right will caus pressure to be developed in chamber 31 between piston 33 and plug 28 and this fluid pressure will be effective on both sides of valve element 48 since it has a loosesliding fit in piston 33.

when the fluid pressure developed by the master cylinder device reaches a predetermined value,.

valve element 48 will be unseated against the bias of spring predetermined value at which valve element 48 becomes unseated depends upon the strength of spring 48 and the area of valveelement 48 ex- 43 of predetermined strength. The.

When the fluid pressure developed by the master cylinder deviceis released, the parts of the compounding unit return to the positions shown in the figures. If the drop in master cylinder developed pressure is rapid, shell [8 will be moved to the left with piston 33, thus unseating valve element 24 and permitting fluid to flow back to the master cylinder device. Spring 36, together with the fluid pressure, will return pistons 33 and 34 to their inoperative positions wherein valve element 48 will again be seated to close the open end of passage 44 through piston 42. The fluid pressure in chamber 31 will be forced out through passage 44 and also around the periphery of cup 43 during the return of the parts to their normally inoperative positions.

The compounding unit just described will not become operative when there is a sudden and rapid actuation of the master cylinder device causing high fiuid'pressllres to be developed instantaneously. These high fluid pressures will not cause unseating of valve element 48 even though they are above the one hundred pounds per square inch at which valve element 48 opens since the restriction of passage 44 by projection 41 does not permit this fluid pressure to become effective immediately on valve element 48 to open it. The high fluid pressures will be transmitted to the fluid motor by way of the check valve before the compounding unit begins to function. Thus the possibility of the compounding unit beginning to function before the fluid pressure in the fluid motor reaches substantially one hundred pounds per square, inch is eliminated under conditions where there is rapid development of fluid pressure by the master cylinder. By preventing the operation of the fluid motor solely by functioning the compounding unit, pedal travel will be saved and also the necessity of a large volume of fluid displacement by the master cylinder device. Even if valve element 48 should be forced off its seat by a momentary high pressure above would be if no compounding acast ma 3 one hundred pounds per square inch, the openclosed by movement of the shell, and means for ing of the valve will permit the fluid under presadmitting fluid pressure from 'the source into the sure present in passage M to drop by diffusing shell at the rear of the piston therein to thereby into the larger chamber 81. When this occurs, v move the piston but only when the fluid pressure the valve element will again closie until the fluid from the source is above a predetermined value. under pressure in passage 44 5 one hundred l. In a fluid pressure system, a source of fluid pounds per square inch. Thus piston 33 would not pressure, a fluid motor, a casing, means for plache moved until such time has elapsed as to permit ing the casing in communication with the source, one hundred pounds per square inch pressure to j conduit means for connecting the casing to the becomg eflective in the fluid motor ill of the brake Hi motor, a shell mounted for limited reciprocation assem ly. in the casing and provided with a cylinder, said l ina w re f t e p s y f mod fi a i ns shell being arranged tobe acted on and moved in the particular structure herein described withby fluid pressure from the source, iston means out departing from the fundamental principles of in the cylinder of the shell and arranged to hav i y I do neeihtend that Its scene be a. smaller area on its forward face than On its rear l d c p as Set fo y the e p face, means for placing the cylinder of the shell claims. I ahead of the piston in communication with the Having fully l ed y invention. What I motor, means for preventing fluid under pressure claim as new and des re to. secure by Letters developed by movement of t piston from Patent of United States municating with the source and comprising valve w 1. In a fluid pressure system, a source fl means closed by movement of the shell, and valve $2.223: fi g gf fi g gz x a 5;; 2 3 35 2 means comprising a biased valve element for ad- I mitting fluid pressure from the source intothe fluid motor and means the mud i r shell at the rear of the piston therein to thereby sure from the source to establish a greater fluid move the piston but only when the fluid pressure g gf the {motor when the g presslurer from the source is above a predetermined value. @9 g soumg 15 above f fi 5. In a fluid pressure system, a source of fluid Q as name means comm smg S pressure, a fluid motozya casing, means for placvided with a cylinder and movable by fluid presing the casing in communication with the source, sure rrom the source and a valve to prevent flow 3h conduit means for connecting the casing to tne or fluid from the motor to the source, a differenmotor, a shell mounted for limited reciprocation rial piston means in the cylinder of the shell in the casing and provided with a cyhnder, said for applying pressure to the fluid in the motor,

shell being arranged to be acted on and moved fluid pressure from said source acting against the by fluid pressure from the source, piston means larger end of said plstonand the smaller and of in the cylinder of the shell and arranged to nave the piston acting on said motor thereby mcreas- I a smaller area on its forward face than on its rear ing the pressure in said motor, and means for a face, means for placing the cylinder of the shell permitting movement of the piston by fluid presh h sure from the source when the pressure therefrom a Bad of t e plston in commumcamon Wlth the a motor, means for preventing fluid under pressure is above the predetermined value.

2. In a fluid pressure system, a source of fluid devetopefi by movement of the Piston i f pressure, a fluid motor means for permitting mumoating with the source and comprising valve fluid pressure from the source to be efiective in means closed by movement? of the shell and valve the fl id motor. and means [f causing the fluid means for admitting fluid pressure from the pressure from'the source to establish a greater some? Into Shell at the rear of the piston fl id pressure In the motor when the fluid pres 4 therein to thereby move the piston but only when sure from the source is above a predetermined the fluid pressure from the Source is above a value, said last named means comprising a Shell determined value, said valve means comprising a ubject to movement pressure from the Valve Seal, Carried Shell, 2, Valve element source, valve means controlled by movement of mounted o the Pismn movement relatively the shell to prevent flow of fluid from the motor 9" thereto and a Spring for biasing the valve to the source, a differential piston in the shell for ment t0 closed Posltionacting" on the fluid effective in the motor, valve In a i Pressure System a Source 0f fluid neans for permitting the fluid pressure from the pressure, fluid 11101701 to be Operated, casing source to flow intothe shell at the rear of the having Stepped cylinders a cylindrical- Shell piston and act thereon when the fluid pressure mounted n h la er cylinder f r limi ipirom the source is above the predetermined value reliable movement, means f r conducting fl i and means associated with the valve means for from the source to the motor through the casing causing a fluid pressure to be developed in th exterior to the shell, said shell being so arranged shell at the rear of the piston prior to the valve as ,to be acted on and moved by fl pressure means being opened. co from the source, a piston in the shell and provided: 3. In a fluid pressure system, a source of fluid with an extension reciprocable in the smaller pressure, a fluid motor, a casing, a shell provided cylinder of the casing. means or ne ting th with a cylinderrand mounted in the casing for interior of the shell forward of the piston with limited reciprocable movement, means for 'placthe motors, means'for connecting the interior of ing the source in communication with th motor the shell at the rear of the piston with the source and for so subjecting the shell to fluid pressure when fluid under pressure therefrom reaches a from the source as to cause it to be moved in one predetermined value, and means comprising valve direction, piston means in the cylinder of the means closed by movement of the shell for preshell and arrangedto have a smaller area on its venting fluid under pressure developed by moveforward face than on its rear face, means for ment of the piston from communicating with the placing the cylinder 01' the shell ahead of the source. 1 piston in communication with themotor, means 7, In a fluid pressure system, a source of fluid for preventing fluid under pressure developed pressure, a fluid motor, a casing provided with by movement or the .piston from communicating stepped cylinders, conduit means for connecting with the source and comprising valve means .the larger cylinder with the source, other conduit pressure from the means for connecting the larger cylinder to the piston in the shell,

the moto means for preventing fluid under pressure developed by movement of theconnected pistons from communicating with the source and comprising valve means closed by movement of the shell when acted on by fluid pressure from the source, spring means for biasing the pistons to an inoperative position and for holding the shell in a position where the valve means is open, and valve means for admitting fluid under pres sure from the source into the shell at the rear of the piston therein to thereby move the piston when the fluid pressure from the source is above a predetermined value.

8. In a fluid pressure system, a source of'fluid pressure, a fluid motor, means for permitting fluid pressure from the source to be eflective in the fluid motor, and means for causing the fluid pressure from the source to establish a greater fluid pressure in the motor when the fluid pressure from the source is above a predetermined value, said last named means comprising a shell provided with a cylinder and movable by fluid source and valve means to prevent flow of fluid from the motor to the source, a differential piston means in the cylinder of the shell for applying pressure to the fluid in the motor, fluid pressure from said source acting against the larger end of said piston and the smaller end of the piston acting on said motor thereby increasing the pressure in said motor, and means for permitting movement of the piston by fluid pressure from the source when the pressure therefrom is above the predetermined value. saidlast named means comprising a valve seat carried by the shell engageable with a valve engaging element on said first mentioned means, a movable valve element carried by the piston and spring means for biasing, the valve element seated.

9. In a fluid pressure system, a source of fluid ressure, a fluid motor, means for permitting fluid pressure from the source to be effective in the fluid motor, and means for causing the fluid pressure from the source to establish a reater fluid pressure in the motor when the fluid pressure from the source is above a predetermined value, said-last named means comprising a-shell provided with a cylinder and movable by fluid pressure from the source and means to prevent flow of fluid from the motor to the source, piston means in the cylinder 01' the shell'ior applying pressure to the fluid in the motor and means for permitting movement of the piston by fluid pressure from the source when the pressure therefrom is above the predetermined value, said last named means comprising a diflerential piston carried by the shell and provided with a passage, fluid pressure from said source acting against the larger end of said piston and the smaller end of the piston acting on said motor thereby increasing the pressure in said motor, a movable valve element carried by the piston for closing the passage, a light spring acting on the last named piston and biasing it toward the valve element, a spring of predetermined strength greater than the light spring acting on me valve element ior biasing it toward closed position and trolled by and provided with an inlet opposing the light spring and spring means acting on the flrst piston means for biasing said piston means to a position in the shell where the valve element closes the passage.

l0. In a compounding unit ior'interpositioning between a conduit conducting fluid under pressure from a source and a conduit conducting fluid under pressure to a fluid motor, said unit comprising a casing having an inlet and an outlet, a cylindrical shell mounted for limited reciprocation in the casing and arranged to be acted on and moved by fluid pressure entering the casing through the inlet, valve means conmovement of the shell when acted on by fluid pressure for cutting between the interior of the shell and the inlet, means for placing the interior of the shell in communication with the outlet, a by-pass around the valve means, a check valve for the by-pass, a

difierential piston in said shell, fluid pressure from said source acting against the larger end of said piston and the smaller end of the piston acting on said motor thereby increasing the pressure in said motor, and means for placing the interior of the shell at the rear and large end of the piston in communication with the inlet when fluid pressure from the source entering the inlet is a predeterminedvalue, the small and front end of the 'piSton connected with the conduit conducting fluid under pressure to said motorl 11. In a compounding unit for interpositioning between a conduit conducting fluid under pressure from a source and a conduit conducting fluid under pressure to a fluid motor, said unit comprising a casing having stepped cylinders at the outer end of the-larger cylinder and an outlet adjacent the inner end of the larger cylinder, a cylindrical shell of smaller external diameter than the larger cylinder of the casing and being mounted in said larger cylinderjor limited reciprocation and arranged to be acted on and moved by fluid pressure entering the. casing through the inlet and passing around the shell to the outlet, a piston in the shell, a piston in the smaller cylinder of the casing, a rod connecting said pistons, valve means controlled by movement of the shell and acted on by fluid pressure for cutting oil communication between. the interior of the shell ahead of the piston therein and the inlet, means for placing the interior of the shell ahead of the piston therein in communication with the outlet at all times, a by-pass around the valve means, a check valve for the by-pass, and means for placing the interior of the shell at the rear of the piston therein in communication with the inlet port when fluid pressure from the source entering the inlet is a predetermined value.

12. In a compounding unit for interpositioning between a conduit conducting fluid under pressure from a source and a conduit conducting fluid under pressure to a fluid motor, said unit comprising a casing having stepped cylinders and provided with an inlet at the outer end of the larger cylinder and an outlet adjacent the inner end of the larger cylinder, a cylindrical shell of smaller external diameter thanthe larger cylinder of the casing and being mounted in said larger cylinder for limited reciprocation and arranged to be acted on and moved by fluid pressure entering the casing through the inlet and passing around the shell to the outlet, 9, piston in the shell, a piston in the smaller cylinder of the casing, a rod connecting said pistons, valve of! communication means controlled by movement of the shell and acted on by fluid pressure for cutting off com munication between the interior of the shell ahead of the piston therein andthe inlet, means for placing the interior of the shell ahead 01' the piston therein in communication with the outlet at all times, a by-pass around the valve means, a check valve for the by-pass, valve means for placing the interior of the shell at the rear of the piston therein in communication with the inlet port when fluid pressure from the source entering the inlet is a predetermined value, and spring means for biasing the piston in the shell to one end thereof and the shell to a position where the valve means controlled thereby is open.

STEVE SCHNELL. 

